/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.runners.core;



import com.bff.gaia.unified.sdk.annotations.Experimental;

import com.bff.gaia.unified.sdk.annotations.Experimental.Kind;

import com.bff.gaia.unified.sdk.state.State;

import com.bff.gaia.unified.sdk.state.StateContext;

import com.bff.gaia.unified.sdk.state.StateContexts;

import com.bff.gaia.unified.sdk.transforms.GroupByKey;



/**

 * {@code StateInternals} describes the functionality a runner needs to provide for the State API to

 * be supported.

 *

 * <p>The SDK will only use this after elements have been partitioned by key. For instance, after a

 * {@link GroupByKey} operation. The runner implementation must ensure that any writes using {@link

 * StateInternals} are implicitly scoped to the key being processed and the specific step accessing

 * state.

 *

 * <p>The runner implementation must also ensure that any writes to the associated state objects are

 * persisted together with the completion status of the processing that produced these writes.

 *

 * <p>This is a low-level API intended for use by the Unified SDK. It should not be used directly, and

 * is highly likely to change.

 */

@Experimental(Kind.STATE)

public interface StateInternals {



  /** The key for this {@link StateInternals}. */

  Object getKey();



  /** Return the state associated with {@code address} in the specified {@code namespace}. */

  default <T extends State> T state(StateNamespace namespace, StateTag<T> address) {

    return state(namespace, address, StateContexts.nullContext());

  }



  /**

   * Return the state associated with {@code address} in the specified {@code namespace} with the

   * {@link StateContext}.

   */

  <T extends State> T state(StateNamespace namespace, StateTag<T> address, StateContext<?> c);

}